Multi-liquid spray gun



April 30,1963 D. J. PEEPS MULTI-LIQUID SPRAY GUN 2 Sheets-Sheet 1 FiledAug. 50, 1960 INVENTOR. D J FEE 06 April 30, 1963 D. J. PEEPSMULTI-LIQUID SPRAY GUN 2 Sheets-Sheet 2 Filed Aug. 30, 1960 INVENTOR. Q(I p6 (yam 86PM United States Patent 3,087,682 MULTI-LIQUID SPRAY GUNDonald J. Peeps, Rossford, Ohio, assignor to The De Vilbiss Company,Toledo, Ohio, a corporation of Ohio Filed Aug. 30, 1960, Ser. No. 52,8354 Claims. (Cl. 239-407) This invention relates to improved sprayapparatus capable of spraying at least two liquids simultaneously from asingle orifice.

Spray guns of the general type referred to above are known in the art.These spray guns can be used with immiscible paints for producingspatter coatings, or can be used with compatible paints of differentcolors or shades to produce various effects in coatings havingtremendous hiding powers. These guns are also useful for spraying thecomponents of resin materials of the slow- 1y reactive type which areadmixed for the first time within the gun, during operation. Spray gunsof this nature heretofore have included two concentric paint supplypassages which open into a chamber through which extends a needle valvefor controlling the flow of paints through an orifice located at one endof the chamber. Two different fluids, however, have a tendency tostratify when moving through the chamber and, therefore, produce erraticpaint deposition or a non-uniform spray pattern. This condition occursto a pronounced extent particularly when the spray gun is left dormantfor awhile and the more dense of the two paints tends to settle in thechamber.

When paints or liquids having different viscosities are used in thetwo-liquid guns heretofore known, the one of lower viscosity tends toflow faster than the one of higher viscosity so that, although theultimate flow of the respective liquids can be controlled bymanually-operated supply valves, the thinner or less viscous materialwill initially tend to flow faster through the orifice from the chamberso that the initial spray has a different color than subsequent spray,even though the pattern is otherwise uniform. The present inventionrelates to an improved construction and location of the liquid tubessupplying the liquids to the chamber, which overcome the above problems.With the liquids supplied through concentric tubes, the inner tube, inaccordance with the invention, is provided with a central dischargehousing located substantially concentrically and coaxially within theliquid chamber with a discharge opening directing the inner liquidthrough the center of the chamber toward the spray orifice. The outerliquid from the outer tube simultaneously flows between the chamber walland the central housing. The two liquids thereby tend to flow ininitially separated concentric paths toward the spray orifice and thetendency for stratification to occur is thus minimized. The dischargehousing also maintains the liquids separately to a point closer to thedischarge orifice so that there is less chance for one of the liquids tosettle, even though the spray gun is at rest for awhile.

Further, in accordance with the principles of the invention, thedischarge housing can have a control orifice at its end through whichthe body of the needle valve extends, the valve body or rod in this casehaving a diameter which closely approximates the diameter of thedischarge opening or control orifice of the housing when the valve is ina closed position, thereby restricting flow of the inner liquid throughthe discharge opening of the housing. However, the valve rod is steppedso that a much thinner portion of it extends through the housingdischarge opening when the needle valve is opened. In this latterposition, the inner liquid can flow quite freely from the housingthrough the discharge opening. Thus,

aasrnsz Patented Apr. 30, 1963 when the needle valve is closed and evenwhen it is slightly open, the flow of the inner liquid supplied throughthe housing is severely restricted, thus substantially reducing its flowwhen the spray gun is initially operated. When the needle valve isopened to its fully opened position, the thinner portion of the valvedoes not seriously impede flow of the inner liquid so that once thevalve is in its normal operating position, the two liquids will flow inthe desired manner. However, until the fully opened position is reached,the flow of the inner liquid is restricted so that if the less viscousof the two liquids is supplied through the housing, the heavier or moreviscous liquid will have a chance to flow initially more rapidly withrespect to the thinner liquid than would otherwise be possible. Thus, auniform spray is obtained even with the initial opening of the spray gunvalve.

It is, therefore, a principal object of the invention to provide amulti-liquid spray gun capable of producing a more uniform spray.

Another object of the invention is to provide a multiliquid spray gun inwhich the liquids tend to settle or stratify within the gun to a lesserextent.

Still another object of the invention is to provide a multi-liquid spraygun which will produce a more uni form flow of two liquids even when thegun is initially operated.

Other objects and advantages of the invention will be apparent from thefollowing detailed description of a preferred embodiment thereof,reference being made to the accompanying drawing, in which:

FIG. 1 is a side view, with parts broken away and with parts in crosssection, of a spray gun embodying the principles of the invention;

:FIG. 2. is a view taken generally along the line 2-2 of Fig. l, Withparts broken away and with parts in cross section;

FIG. 3 is a detailed view in vertical cross section on an enlarged scaleof a discharge housing embodying the principles of the invention andutilizing a stepped needle valve body shown in a closed position; and

FIG. 4 is a view in cross section similar to FIG. 3 but with the steppedneedle valve body shown in a fully opened position.

Referring to the drawing, and more particularly to FIG. 1, a spray gunembodying the invention is indicated by the numeral 10. However, it isto be understood that the invention can be incorporated with many typesof multi-liquid spray guns and is not limited to the particular oneillustrated and described. The spray gun 10 in cludes a gun body 12carrying a spray cap 14 which is provided witha plurality of atomizingair ports 16 and an annular air port 18. Air for these ports is suppliedfrom a suitable source through a flexible hose to a fitting 2t) and,hence, through an inlet passage 22 to a valve 24 which seats on anannular end of a valve seat member 26, the valve 24 being operatedthrough a trigger rod 28 and a trigger 30 pivoted to the body 12 at 32.When the valve 24 is open, the air continues through a passage 34,through ports 36 in a cylindrical member 38, and through a longitudinalpassage 40. From the passage 40, the air travels through an annularmanifold 42, an annular space 44, and a plurality of small restrictedpassages 46 to the ports 16 and 18. Any suitable air control system may,of course, be substituted for the one described.

Coating liquid is discharged from the gun body 12 and the cap 14 througha central orifice 48 from a liquid chamber 50 therebehind andsubstantially concentric of the gun body. Flow of liquid through theorifice 48 from the chamber is controlled by an elongated needle valve52 which extends through valve packing '54 held by a packing nut 56 atthe rear of the chamber 50. The rod passes through a slot 58 in thetrigger 30 to an enlarged, cylindrical stop 60 against which the trigger30 abuts when squeezed to pull the valve rod 52 rearwardly and open theorifice 48. The cylindrical stop 60 extends into a barrel 62 containinga spring 64 which contacts the stop 60 and urges the valve rod 52 intoliquid-tight engagement with the orifice 48. A cap 66 is threaded intothe end of the barrel 62 and can be screwed inwardly and outwardly tovary the amount of compression on the spring 64 and to limit therearward movement of valve 52.

The coating liquid is supplied to the liquid chamber 50 from separatepressure tanks 68 and 70, through flexible tubing 72 and 74- which areconnected to passages 76 and '78 (FIG. 2) in a fitting 80. Flow throughthe passages 76 and 78 is controlled by manually operated valves 82 and84. Liquid in the passage 76 flows through an outer passage 86 in thegun body 12 and, hence, into the rear portion of the chamber 50. Liquidin the passage 78 flows through an inner passage 88 locatedconcentrically within the passage 86 and which is connected with anopening 90 in a liquid housing 92.

The liquid housing 92 in accordance with the invention is located andmaintained concentrically and coaxially with the chamber 50 with the aidof laterally projecting fins or ribs 93. The housing has a rear opening94 through which the needle valve body 52 extends in close proximity anda discharge opening 96 at the front portion of the housing 92 throughwhich liquid supplied through the tubing '74 and the passages 78 and 88is emitted toward the orifice 48. This inner liquid is thus separatedfrom and flows substantially concentrically with the other liquid fromthe passage 86 toward the orifice 48 and reduces stratification to aminimum. Because of the length of the housing 92, the two liquids arealso separated in the chamber 50 to a point closer to the liquid orifice48 whereby the two liquids have a lesser chance to mix and settle whenthe gun is not in use. Even where settling does occur, a such smallerproportion settles than is true with conventional multi-liquid sprayguns which supply both fluids at the rear of the chamber.

If the housing 92 is short enough, it can be inserted into the gun, withthe tube forming the inner passage 88, through the outer passage 86.Otherwise, the housing 92 and the tube or passage member 88 areassembled after being positioned in the chamber 50, as, for example, bya threaded engagement.

Referring to FIGS. 3 and 4, a modified housing 98 embodying theprinciples of the invention is particularly adapted for spraying liquidsof diflerent viscosities, the liquid having the lower viscosity beingsupplied to the inner passage. The housing 98 is similar to the housing92, including a rear or valve rod opening 100 and a discharge opening102, which in this instance, are of the same diameter. The housing 98communicates with the passage 90 which extends through the passage 88,as is also true in FIGS. 1 and 2. A modified valve rod 104, extendingthrough the housing 98, has an enlarged portion 106 and a stepped downend portion 108. When the needle valve 104 is in its closed position, asshown in FIG. 3, the enlarged portion .106 extends through both of theopenings 100 and 2, thereby substantially closing oti the interior ofthe housing 98 from the liquid chamber 50. As the needle valve 104 isopened by being pulled rearwardly, the enlarged portion 106 retractsfrom the discharge opening 102 until it reaches its fully openedposition (FIG. 4) with the trigger 30 fully retracted, leaving thedischarge opening 102 relatively free for the passage of the innerliquid from the inner passage 88. As the stepped down end 108 of thevalve 104- moves away from the liquid orifice 4,8, the discharge orifice102 of the housing 98 remains substantially restrictedv until a morefully opened position of the valve 104 is reached. This enables theouter fluid, which may be the more viscous of the two, to flow initiallywhile the inner, less viscous fluid is still restricted by the largeportion 106 of the valve 104. If desired, the stepped down portion ofthe valve 104 may be somewhat tapered, rather than being sharply cut, asshown. The proper ratio of the diameters of the portions 106 and 108will also depend on the relative viscosities of the liquids used.

Various modifications of the above described embodiments of theinvention will be apparent to those skilled in the art and it is to beunderstood that such modifications can be made without departing fromthe scope of the invention, if within the spirit and tenor of theaccompanying claims.

What I claim is:

1. In a spray gun body including an air passage, a liquid chamber, meansforming two liquid passages for supplying coating liquid to saidchamber, a liquid orifice communicating with said liquid chamber, an airnozzle spaced from said liquid orifice and communicating with said airpassage, a needle valve having an end associated with said liquidorifice for opening and closing the same, said needle valve extendingsubstantially concentrically through said liquid chamber and out of saidgun body, means for opening and closing said needle valve, and meansassociated with said opening and closing means for controlling flow ofair through said air passage, the improvement comprising a liquidhousing located substantially concentrically in said liquid chamber andhaving a discharge opening directed toward said liquid orifice, a valverod opening aligned with said discharge opening and spaced therefrom,and another opening communicating directly and solely with one of saidpassages and positioned between said valve rod opening and saiddischarge opening, said needle valve extending through said dischargeopening and said valve rod opening, the portion of said needle valveextending through said discharge opening when said needle valve isopened being smaller than the diameter of said discharge opening.

2. In a spray gun body including an air passage, a liquid chamber, meansforming two concentric liquid passages for supplying coating liquid tosaid chamber, a liquid orifice communicating with said liquid chamber,an air nozzle spaced from said liquid orifice and communicating withsaid air passage, a needle valve having an end associated with saidliquid orifice for opening and closing the same, said needle valveextending substantially concentrically through said liquid chamber andout of said gun body, means for opening and closing said needle valve,and means associated with said opening and closing means for controllingflow of air through said air passage, the improvement comprising aliquid housing located substantially concentrically in said liquidchamber and having a discharge opening directed toward said liquidorifice, a valve rod opening aligned with said discharge opening andspaced therefrom, and another opening communicating directly and solelywith the inner one of said concentric passages and positioned betweensaid valve rod opening and said discharge opening, said needle valveextending through said discharge opening and said valve rod opening, theportion of said needle valve extending through said discharge openingwhen said needle valve is opened being smaller than the diameter of saiddischarge opening.

3. In a spray gun body including an air passage, a liquid chamber, meansforming two liquid passages for supplying coating liquid to saidchamber, a centrally located liquid orifice communicating with saidliquid chamber, an air nozzle spaced from said liquid orifice andcommunicating with said air passage, a needle valve having an endassociated with said liquid orifice for opening and closing the same,said needle valve extending substantially concentrically through saidliquid chamber and out of said gun body, means associated with saidneedle valve and located outside said gun body for opening and closingsaid needle valve, and means associated with said opening and closingmeans for controlling flow of air through said air passage, theimprovement comprising said needle valve having a first portion closerto said liquid orifice of small diameter and a second portion away fromsaid liquid orifice, but at least partly within said liquid chamber, oflarger diameter, a liquid housing located substantially concentricallyin said liquid chamber and having a discharge opening directed towardsaid liquid orifice, a valve rod opening spaced from said dischargeopening, and another opening communicating directly and solely with oneof said passages and positioned between said valve rod opening and saiddischarge opening, said discharge opening having a diameter slightlylarger than the diameter of said second needle valve portion and saidvalve rod opening also having a diameter slightly larger than thediameter of said second needle valve portion, part of said second needlevalve portion extending through said discharge opening when said needlevalve is closed and part of said first needle valve portion extendingthrough said discharge opening when said needle valve is fully opened.

4. In a spray gun body including an air passage, a liquid chamber, meansforming two concentric liquid passages for supplying coating material tosaid chamber, a centrally located liquid orifice communicating with saidliquid chamber, an air nozzle spaced from said liquid nozzle andcommunicating with said air passage, a needle valve having an endassociated with said liquid orifice for opening and closing the same,said needle valve extending substantially concentrically through saidliquid chamber and out of said gun body, means associated with saidneedle valve and located outside said gun body for opening and closingsaid needle valve, and means associated with said opening and closingmeans for controlling flow of air through said air passage, theimprovement comprising said needle valve having a first portion closerto said liquid orifice of small diameter and a second portion away fromsaid liquid orifice, but at least partly within said liquid chamber, oflarger diameter, a housing located substantially concentrically in saidliquid chamber and having a discharge opening directed toward saidliquid orifice, a valve rod opening and spaced therefrom, and anotheropening communicating directly and solely with the inner one of saidconcentric passages and positioned between said valve rod opening andsaid discharge opening, said discharge opening having a diameterslightly larger than the diameter of said second portion and said valverod opening also having a diameter slightly larger than the diameter ofsaid second portion, part of the second portion extending through saiddischarge opening when said needle valve is closed and pant of saidfirst portion extending through said discharge opening when said needlevalve is fully opened.

References Cited in the file of this patent UNITED STATES PATENTS1,470,111 Biersdorf Oct. 9, 1923 2,265,209 Thompson Dec. 9, 19412,511,626 Einbecker June 13, 1950 2,513,081 Clark et al June 27, 19502,786,716 Peeps Mar. 26, 1957 FOREIGN PATENTS 508,288 France Jan. 10,1920

1. IN A SPRAY GUN BODY INCLUDING AN AIR PASSAGE, A LIQUID CHAMBER, MEANSFORMING TWO LIQUID PASSAGES FOR SUPPLYING COATING LIQUID TO SAIDCHAMBER, A LIQUID ORIFICE COMMUNICATING WITH SAID LIQUID CHAMBER, AN AIRNOZZLE SPACED FROM SAID LIQUID ORIFICE AND COMMUNICATING WITH SAID AIRPASSAGE, A NEEDLE VALVE HAVING AN END ASSOCIATED WITH SAID LIQUIDORIFICE FOR OPENING AND CLOSING THE SAME, SAID NEEDLE VALVE EXTENDINGSUBSTANTIALLY CONCENTRICALLY THROUGH SAID LIQUID CHAMBER AND OUT OF SAIDGUN BODY, MEANS FOR OPENING AND CLOSING SAID NEEDLE VALVE, AND MEANSASSOCIATED WITH SAID OPENING AND CLOSING MEANS FOR CONTROLLING FLOW OFAIR THROUGH SAID AIR PASSAGE, THE IMPROVEMENT COMPRISING A LIQUIDHOUSING LO-